Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

850
FXUS63 KLOT 151957
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
257 PM CDT Wed Apr 15 2026

.KEY MESSAGES...

- Additional period of showers and thunderstorms expected this
  evening. Some could be strong and produce heavy rainfall
  leading to localized flash flooding.

- A brief break in the pattern is expected late Thursday into
  the day on Friday before another storm system arrives Friday
  evening into early Saturday.

- Cooler air arrives into early next week and may bring
  frost/freeze concerns early Sunday and Monday mornings.

&&

.DISCUSSION...
Issued at 257 PM CDT Wed Apr 15 2026

Through Thursday...

The primary weather focus in the near continues to revolve
around the expectation for additional rounds of showers and
thunderstorms, particularly this evening.

A recent surface analysis indicates that an area of low
pressure resides across southeastern NE, with an associated
surface cold front extending south-southwestward into the TX
Panhandle. While our area has remained cloudy, increased
insolation west of the area in the vicinity of the surface low
and frontal boundary continues to destabilize the very moist
(dew points in the low to mid 60s) low-level prefrontal airmass
across MO into south central IA. This will set the stage for
additional thunderstorm development mid to late this afternoon
west of our area as increased forcing for ascent associated with
the mid-level impulse ejecting into the Mid-Missouri Valley
overspreads the frontal boundary. After storms onset, a gradual
upward growth into an MCS is anticipated this evening as they
shift eastward across the Mississippi river. It appears the
primary severe weather threat with these storms will be west of
our area, with storms likely to be on a weakening trend as they
progress eastward across northern IL during the mid to late
evening hours. Nevertheless, a continued favorable kinematic
environment overhead may continue to support a threat for
localized strong wind gusts with the weakening line of storms.

Heavy rainfall is expected to accompany these storms through
the evening, and this does continue to add concerns for possible
hydro concerns tonight. However, it appears the heaviest rain
rates may remain more progressive with the moving line of storms
tonight. Accordingly, it appears the threat for significant
flash flooding is lower than previously thought. Nevertheless,
areas across far northern IL that received heavy rainfall last
night will be most at risk for additional flooding concerns.,
With this in mind, we have opted to hold onto the going flash
flood watch for this evening.

Shower and thunderstorm coverage is expected to become more
widely scattered overnight tonight into Thursday as the main
mid-level impulse shifts overhead. As an afternoon lake breeze
develops and pushes inland across northeastern IL and
northwestern IN Thursday afternoon in the wake of the surface
low, this may act as a focus for additional isolated shower
activity for a few hours Thursday afternoon. Outside of this,
conditions will be drying out Thursday afternoon and evening.

KJB

Friday - Saturday:

Strong southerly warm and moist convection will return into the
day on Friday ahead of an approaching cold front. This boundary
is expected to progress across the area sometime late Friday
into early Saturday morning paired with a line of thunderstorms,
some of which could be severe. Suspect that less favorable
diurnal timing of any lingering storms into the morning on
Saturday may limit the overall severe threat here locally before
storms reintensify east of the area into the rest of the day.
Stay tuned!

Saturday night onward:

In the wake of the early Saturday cold front, a much colder
airmass (relative to what we have had over the past several
days) will settle into the region over the weekend. Overnight
low temperatures may drop into the 30s, with some near to sub-
freezing temperatures possible across interior northern
Illinois. Lighter winds in place Sunday night may allow for
frost development outside of Chicago and will be something for
those with agricultural interests to monitor over the next few
days.

The cooler conditions will be rather short-lived with extended
guidance favoring a return toward high amplitude ridging across
the central CONUS and unseasonably warm temperatures returning
to the region by midweek next week.

Petr

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1245 PM CDT Wed Apr 15 2026

Key Aviation Messages for the current TAF period:

- Lingering VFR showers through this afternoon with gusty
  southwest winds

- Two rounds of storms with better chances at/near terminals
  late this afternoon through midnight. Some of these storms
  could be strong to severe.

- Weaker showers fester through tomorrow morning.

- Wind shift to the northeast tomorrow afternoon

A surface low, currently analyzed just north of Kansas City,
Missouri, will move east-northeast through today and the
overnight. This low will be the driving force behind the shower
and storm threat tonight. In the meantime, weak rain showers
persist this afternoon out ahead of it. Winds will remain out of
the southwest through most of the TAF window, with persistent
gusts 20 to 25 knots, not diminishing until after midnight.

As the low moves closer, it will push a warm front northward
through Illinois for the first wave of showers and thunderstorms
this evening. There could be a dry slot for a couple hours, but
then as the low passes north of the area, it will drag a cold
front across northern Illinois for a second round of showers and
thunderstorms across the airspace. Some of these storms could
become strong to even severe, producing hail and erratic,
strong wind gusts.

As the front moves east, showers could fester through the
morning. There is lower confidence in ceiling trends due to
model disagreement, but erred more cynical behind the low and
forecasted widespread MVFR conditions across the region through
the morning. Winds will become more westerly in the morning, but
as the low continues its journey east of the area, models are
suggesting a weak front will be sent southward across Lake
Michigan and switch winds over to the northeast tomorrow
afternoon.

DK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Flood Watch until 1 AM CDT Thursday for ILZ003-ILZ004-ILZ005-
     ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-ILZ019-ILZ020-
     ILZ021-ILZ023-ILZ032-ILZ103-ILZ104-ILZ105-ILZ106-ILZ107-
     ILZ108.

IN...Flood Watch until 1 AM CDT Thursday for INZ001-INZ002-INZ010-
     INZ011.

LM...None.

&&

$$

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